The invention relates to a roller conveyor.
Accumulating roller conveyors are often used for the pressureless storage and conveyance of piece goods and are provided with rotatably held support rollers which are combined into groups of rollers, with a drivable and brakable roller being provided in each group of rollers.
A roller conveyor of the kind mentioned above is known from EP 0 586 624 B1. In this conveyor, a motor roller is provided in each group of rollers in which an electromotor with a planetary gear is provided. Each of the motor rollers which is each assigned to one group of rollers can be driven individually.
This leads to the disadvantage of a relatively high complexity in the installation and circuitry. Relatively high motor currents are also obtained during operation. Moreover, said motor rollers cannot be arrested and the braking moment that can be achieved with such a motor roller is substantially defined by the planetary gear.
A further roller conveyor has become known from EP 0446 992 B1. It describes a roller drive device in which the drive and the arresting of the drivable and brakable roller is performed exclusively by way of pneumatically actuatable elements which are arranged within the roller.
This solution leads to the disadvantage of a relatively high complexity of installation and circuitry which is caused by the pneumatic elements. Moreover, this roller conveyor requires a high amount of energy and produces a considerable level of noise during the switching of the pneumatic elements.
It is the object of the present invention to avoid such disadvantages and to provide a roller conveyor of the kind mentioned above which is characterized by a simple arrangement.
This is achieved in accordance with the invention by a roller conveyor comprising a frame, several sections of rollers held in the frame; each section comprising a plurality of support rollers, a drivable and brakable roller coupled to the support rollers, and a drive roller; a common axle rotatably supporting the drive roller and the drivable and brakable roller; a first switchable electromechanical clutch connecting the drivable and brakable roller to the drive roller; and a second switchable electromechanical clutch connecting the drivable and brakable roller to a braking drive.
The proposed measures lead to the advantage that the drivable and brakable roller of each group of rollers can be coupled with the drive roller on the one hand by way of simple electromagnets and can be braked and arrested on the other hand by way of a further electromagnet.
The installation effort is relatively low because it is merely necessary to lay relatively small dimensioned electric lines and it is possible to omit pneumatic lines and accumulating storages.
Preferably, the first electro mechanical clutch comprises a ring magnet which is held non-rotationally on the axle and magnetizes the drive roller, a friction lining on a side of the drive roller facing the drivable and brakable roller, and an armature non-rotationally connected to the drivable and brakable roller and held axially displaceably thereon for contact with the friction lining. Because the ring magnet is held in a stationary manner, it can be supplied via connecting lines which are guided along the axis for example. The magnetic flux from the pole faces of the ring magnet to the armature is conducted via the magnetizable ring. A high efficiency of the ring magnet is thus achieved.
The second electromechanical clutch preferably comprises a ring magnet which is held non-rotationally on the axle and has a pole face provided with a friction lining, and an armature non-rotationally connected to the drivable and brakable roller and held axially displaceably thereon. This allows keeping the ring magnet stationary and a simple connection of the ring magnet is thus also possible.
If a common revolving drive belt drives the drive rollers of the several sections, all rollers cane be driven with a single drive.
Preferably, belts operatively connect the drivable and brakable roller of each section of rollers with the support rollers thereof. This has the advantage of a very simple coupling of the rollers of each section of rollers with the associated drivable and brakable roller.